1. Technical Field
The present invention relates in general to improvements in removable electronic subassemblies which must fit into an aperture of a data processing system defining a selected form factor, and in particular to an improved removable electronic subassembly having a compressible shock absorbing layer which does not conform to the predetermined form factor when outside the aperture, but which can be compressed to fit within the aperture of the data processing system.
2. Description of the Related Art
The use of removable electronic subassemblies in conjunction with data processing systems is continually increasing in the computer field. Removable electronic subassemblies such as disk drives, modems, network interfaces, and the like are often used in conjunction with data processing systems such as computers and the like. For purposes of interchangeability, the removable electronic subassemblies are required to fit into an aperture defining a selected "form factor" in the data processing system.
With the increased use of removable electronic subassemblies and the decrease in size of the same, it is becoming increasingly more common to transport the removable electronic subassemblies while not connected to or inserted within the data processing system. While being transported, the removable electronic subassemblies are frequently dropped and inadvertently tossed around. To avoid damage to the removable electronic subassemblies, these subassemblies must be able to withstand a certain amount of shock.
It has been a continuing objective of the computer industry to increase the capacity and functions of any given size of removable electronic subassembly. In order to increase the capacity or functions of the various removable electronic subassemblies it is desired to have increased usable volume for the inner working components. The maximum exterior dimensions of the removable electronic subassembly, however, are dictated by the form factor of the aperture of the data processing system within which the removable electronic subassembly must fit.
To allow the removable electronic subassemblies to withstand a certain amount of shock, a certain amount of the usable volume must be used for shock absorbing devices, thereby decreasing the amount of volume available for the inner working components of the removable electronic subassembly. Alternatively, the use of shock absorbing devices can be minimized, but the interior components of the removable electronic subassembly must be stronger and more rugged so as to withstand an increased amount of shock. When components are made stronger and more rugged they also increase in size, therefore decreasing the capacity of the removable electronic subassembly.
With the continuing trend in the computer industry to reduce the volume of the data processing systems, it has also become necessary to reduce the size of the aperture within which the removable electronic subassemblies must fit. Therefore, the removable electronic subassemblies must have increasingly smaller form factors. One example of removable electronic subassemblies which must have small form factors are PCMCIA devices. PCMCIA is an acronym for Personal Computer Memory Card International Association. PCMCIA devices are usually about two to three inches wide and three to four inches long. PCMCIA devices have various standard thicknesses ranging from just a few millimeters to about ten millimeters. All the necessary components for devices such as disk drives, modems, and the like must fit within such small volumes.
PCMCIA devices are expected to handle high shock inputs, and are expected to be rugged for ease of portability. The industry standards for PCMCIA devices require that such devices survive drops of 30 inches onto a cushionless floor or desk, the purpose being to allow such devices to be carried around like inexpensive calculators or cassette cartridges.
Achieving the desired shock and fragility resistance for such devices is not so much a challenge, as is meeting these requirements within space and cost constraints. As discussed above, shock absorbing devices can be easily provided, but at the expense of usable volume. The use of shock absorbing devices greatly reduces the shock felt by the inner components, thereby avoiding the need of shock resistant inner components. However, the amount of volume lost to shock absorbing devices greatly restricts the capacity and functions of the devices. Alternatively, less volume can be used for shock absorbing devices, but this requires stronger and more shock resistant inner components. In addition to adding to the cost of the devices, stronger and more shock resistant inner components are also generally thicker and larger and therefore do not allow the device to obtain its maximum capacity and function.